Help with randomly replacing values in dataframe with NA

[nirgrahamuk]

Perhaps this recent thread will help you

Randomly Replace Values with NA

I am working the R programming language. I am trying select 10% of the elements in my dataset (excluding elements in the first column) and replace them with NA. I tried to do this with the following code: library(longitudinalData) data(artificialLongData) second_dataset = artificialLongData second_dataset[sample(nrow(second_dataset),0.1*nrow(second_dataset ))]<- NA This produces the following error: Error in `[<-.data.frame`(`*tmp*`, sample(nrow(second_dataset), 0.1 * : new columns would leave holes after existing columns Can someone please show me how to fix this problem? Thanks! Note: The final result should look something like this: id t0 t1 t2 t3 t4 t5 …